The present invention relates to the co- and terpolymerization of monomers of ethylene, other olefins, and alkynes and mixtures thereof, with carbon monoxide, and more particularly to a polymerization catalyst for the same.
It is well known that ethylene and 1-olefins can be polymerized with a Ziegler-type catalyst derived from a transition metal halide and an aluminum alkyl. Ziegler-type catalysts, however, are rare when the transition metal is a late transition metal, such as a Group VIII metal. Also, aluminum alkyl is a pyrophoric liquid and hazardous to use.
In addition, in some early transition metal systems having a cationic species and an anionic species, there appears to be a reaction between the cationic species and the anionic species which deactivates the active cationic species, and more particularly the catalyst. Thus, attempts have been made to stabilize the active cationic species with a different anionic species. For example, it has been proposed in U.S. Pat. Nos. 4,791,180 to Turner and 4,794,096 to Ewen to use excess amounts of alumoxane with various active cationic Ziegler-type catalysts. These catalysts, however, typically require an undesirable excess of the alumoxane (i.e., greater than about 1:1000 weight ratio of catalyst to alumoxane). Moreover, these catalysts are highly subject to poisoning with basic impurities.
It has also been proposed in EPO Patent Nos. 0,277,003 and 0,227,004, both to Turner, to use an anionic species comprising a plurality of boron atoms to stabilize active cationic species based on zirconium, titanium or hafnium. However, the types of monomers and solvents which may be used with cationic species based on early transition metals is limited because of the incompatibility of these metals with monomers and solvents bearing functional groups.
Various catalysts to copolymerize carbon monoxide and olefins have been proposed. For example, a catalyst to copolymerize carbon monoxide and at least one olefinically unsaturated hydrocarbon has been proposed in U.S. Pat. Nos. 4,788,279 and 4,786,714, both to Drent. The catalyst is obtained by the reaction of a Group VIII metal compound with a nitrogen bidentate ligand, an anion of a non-hydrohalogenic acid having a pKa of less than 6 (e.g., sulfuric acid, perchloric acid, sulfonic acids and carboxylic acids), with or without an organic oxidant. However, polymers formed using such catalysts tend to have a wide and variable molecular weight distribution thus reducing the potential commercial utility thereof. Moreover, such catalysts tend to require more severe reaction conditions, e.g., high pressure and high temperatures.
Thus, it would be highly desirable to provide a catalyst for the co- and terpolymerization of monomers of ethylene, other olefins, and alkynes with carbon monoxide which is stable at a wide variety of temperatures, is resistant to impurities, is not hazardous to make and use, and is capable of being used with a wide variety of monomers and solvents including those with functional groups. It would also be desirable to provide a catalyst which provides a controlled molecular weight and a narrow molecular weight distribution of the polymer formed during the co- or terpolymerization process. Such a controlled molecular weight and narrow molecular weight distribution facilitates the tailoring of polymer properties such as melting point, glass transition temperature, crystallinity, etc.